Closing the Gap: Towards a Fully Continuous and Self-Regulated Kolbe Electrosynthesis.

In this article, we address the transition of the Kolbe electrolysis of valeric acid (VA) to n-octane as an exemplary electrosynthesis process from a batch reaction to a continuous, self-regulated process. Based on a systematic assessment of chemical boundary conditions and sustainability aspects, we propose a continuous electrosynthesis including a simple product separation and electrolyte recirculation, as well as an online-pH-controlled VA feeding. We demonstrate how essential performance parameters such as product selectivity (S) and coulombic efficiency (CE) are significantly improved by the transition from batch to a continuous process.

Insight into the Interaction of Furfural with Metallic Surfaces in the Electrochemical Hydrogenation Process.

Electrocatalytic hydrogenation of furfural on metal surfaces has become an important research subject due to the potential of the reaction product 2-methylfuran as a renewable energy resource. Identifying effective determinants in this reaction process requires a thorough investigation of the complex electrode-electrolyte interactions, which considers a variety of the influential components. In this work, in operando electrochemical Raman Spectroscopy and Molecular Dynamics simulations were utilized to investigate different characteristics of the interface layer in the electrocatalytic hydrogenation of furfural.

Comparison of different salt solutions for density separation of conventional and biodegradable microplastic from solid sample matrices.

Microplastics are the new emerging pollutants ubiquitously detectable in aquatic and terrestrial ecosystems. Fate and behavior, as well as ecotoxicity, are of increasing environmental concern, particularly in sediments and soils as natural sinks. For a global environmental risk assessment, reliable and easy to apply analytical methods are mandatory to obtain comparable data.

Introducing Alternative Algorithms for the Determination of the Distribution of Relaxation Times.

Impedance spectroscopy is a powerful characterization method to evaluate the performance of electrochemical systems. However, overlapping signals in the resulting impedance spectra oftentimes cause misinterpretation of the data. The distribution of relaxation times (DRT) method overcomes this problem by transferring the impedance data from the frequency domain into the time domain, which yields DRT spectra with an increased resolution.

Bidirectional electroactive microbial biofilms and the role of biogenic sulfur in charge storage and release.

The formation of combined electrogenic/electrotrophic biofilms from marine sediments for the development of microbial energy storage systems was studied. Sediment samples from the German coasts of the Baltic and the North Sea were used as inocula for biofilm formation. Anodic biofilm cultivation was applied for a fast and reproducible biofilm formation.

How Comparable are Microbial Electrochemical Systems around the Globe? An Electrochemical and Microbiological Cross-Laboratory Study.

Invited for this month's cover is the collaborative work among Univ. of Milano-Bicocca, Ricerca sul Sistema Energetico S.p.

Direct and Indirect Electrooxidation of Glycerol to Value-Added Products.

In this work, different approaches for the direct and indirect electrooxidation of glycerol, a by-product of oleochemistry and biodiesel production, for the synthesis of value-added products and of intermediates for biofuel/electrofuel production, were investigated and compared. For the direct electrooxidation, metallic catalysts were used, whose surfaces were modified by promoters or second catalysts. Bi-modified Pt electrodes (Pt Bi /C) served as model systems for promoter-supported electrocatalysis, whereas IrO -modified RuO electrodes were studied as catalyst combinations, which were compared under acidic conditions with the respective monometallic catalysts (Pt/C, RuO /Ti, IrO /Ti).

Reclaimed water driven lettuce cultivation in a hydroponic system: the need of micropollutant removal by advanced wastewater treatment.

For a novel approach of resource-efficient water reuse, a municipal wastewater treatment plant was extended at pilot scale for advanced wastewater treatment, i.e., ozonation and biological activated carbon filtration, and a hydroponic system for reclaimed water driven lettuce cultivation.

How Comparable are Microbial Electrochemical Systems around the Globe? An Electrochemical and Microbiological Cross-Laboratory Study.

A cross-laboratory study on microbial fuel cells (MFC) which involved different institutions around the world is presented. The study aims to assess the development of autochthone microbial pools enriched from domestic wastewater, cultivated in identical single-chamber MFCs, operated in the same way, thereby approaching the idea of developing common standards for MFCs. The MFCs are inoculated with domestic wastewater in different geographic locations.

Customizable design strategies for high-performance bioanodes in bioelectrochemical systems.

Bioelectrochemical systems (BESs) can fulfill the demand for renewable energy and wastewater treatment but still face significant challenges to improve their overall performance. Core efforts have been made to enhance the bioelectrode performance, yet, previous approaches are fragmented and have limited applicability, unable to flexibly adjust physicochemical and structural properties of electrodes for specific requirements in various applications. Here, we propose a facile electrode design strategy that integrates three-dimensional printing technology and functionalized modular electrode materials.

Studying the Impact of Wall Shear Stress on the Development and Performance of Electrochemically Active Biofilms.

A laminar flow reactor was designed that provides constant and reproducible growth conditions for the bioelectrochemical observation of electroactive bacteria (EAB). Experiments were performed using four reactors in parallel to enable the comparison of EAB growth behavior and bioelectrochemical performance under different hydrodynamic conditions while simultaneously keeping biological conditions identical. With regard to the moderate flow conditions found in wastewater treatment applications, the wall shear stress was adjusted to a range between 0.

Optimal Geometric Parameters for 3D Electrodes in Bioelectrochemical Systems: A Systematic Approach.

In this study, the performance of electroactive bacteria (EAB), cultivated inside tubular electrode ducts, is systematically investigated to derive predictions on the behavior of EAB under conditions limited by electrochemical losses. A modeling approach is applied to assess the influence of the electrochemical losses on the electrochemical performance and scaling characteristics of complex 3D structures, such as sponges and foams. A modular flow reactor is designed that provides laminar and reproducible flow conditions as a platform for the systematic electrochemical and bioelectrochemical characterization of 3D electrodes in bioelectrochemical systems (BES).

Development and characterization of a fiber optical fluorescence sensor for the online monitoring of biofilms and their microenvironment.

The growth of microorganisms on surfaces and interfaces as a biofilm is very common and plays important role in various areas such as material science, biomedicine, or waste treatment among others. Due to their inhomogeneous structure and the variance in the microorganism consortium, the analysis of biofilms represents a significant challenge. An online fluorescence sensor was developed that is able to measure the most important biological fluorophores (proteins, nicotinamide adenine dinucleotide, and flavin) in a noninvasive manner in biofilms, e.

Development of biofilm collectors as passive samplers in sewerage systems-a novel wastewater monitoring method.

In this study, a novel wastewater sampling method based on biofilm collection on a multi-armed polyethylene strips (so called "Octopus") is proposed. The implementation of this method is a step forward to prevent illegal industrial discharges into sewerage systems and receiving water bodies. Prior applications of biofilm collection were performed in Bielefeld, Germany, in 1994.

The Limits of Three-Dimensionality: Systematic Assessment of Effective Anode Macrostructure Dimensions for Mixed-Culture Electroactive Biofilms.

This study analyzes the biofilm growth and long-term current production of mixed-culture, electrochemically active biofilms (EABs) on macrostructured electrodes under low-shear-force conditions. The channel dimensions were altered systematically in the range 400 μm to 2 mm, and the channel heights were varied between 1 and 4 mm to simulate macrostructures of different scales. Electrodes with finer-structured surfaces produced higher current densities in the short term owing to their large surface area but were outperformed in the long term because the accumulation of biomass led to limitations of mass transfer into the structures.

Long-Term Behavior of Defined Mixed Cultures of and in Bioelectrochemical Systems.

This work aims to investigate the long-term behavior of interactions of electrochemically active bacteria in bioelectrochemical systems. The electrochemical performance and biofilm characteristics of pure cultures of and are being compared to a defined mixed culture of both organisms. While pure cultures did not form cohesive and stable biofilms on graphite anodes and only yielded 0.

A practice-oriented method for the analysis of coplanar tetra- to heptachlorinated terphenyls.

Polychlorinated terphenyls (PCT) were produced and used on industrial scale in the last century. Today, PCT are formed especially during combustion and some chemical conversion processes. As being persistent, low volatile chlorinated aromatics, they are continuously emitted into the environment from primary and secondary sources.

Integrated Valorization of Desalination Brine through NaOH Recovery: Opportunities and Challenges.

The rising use of seawater desalination for fresh water production is driving a parallel rise in the discharge of high-salinity brine into the ocean. Better utilization of this brine would have a positive impact on the energy use, cost, and environmental footprint of desalination. Furthermore, intermittent renewable energy can easily power the brine utilization and, for reverse osmosis technology, the entire desalination plant.

Use of torsional resonators to monitor electroactive biofilms.

Whereas the study of interfaces and thin films with the quartz crystal microbalance (QCM) is well established, biofilms have proven to be a difficult subject for the QCM. The main problem is that the shear wave emanating from the resonator surface does not usually reach to the top of the sample. This problem can be solved with torsional resonators.

Towards selective electrochemical conversion of glycerol to 1,3-propanediol.

1,3-propanediol (1,3-PD) is a bulk chemical with myriad applications in polymers, lubricants, cosmetics, foods industries and in the synthesis of heterocyclic compounds. Current commercial production of 1,3-PD involves a thermocatalytic process using acrolein (DuPont) and ethylene oxide (Shell) as starting feedstock. These feedstocks are petroleum-based and there are many efforts at using glycerol as low cost biomass-derived feedstock for 1,3-PD production.

Bulk soil and maize rhizosphere resistance genes, mobile genetic elements and microbial communities are differently impacted by organic and inorganic fertilization.

Organic soil fertilizers, such as livestock manure and biogas digestate, frequently contain bacteria carrying resistance genes (RGs) to antimicrobial substances and mobile genetic elements (MGEs). The effects of different fertilizers (inorganic, manure, digestate) on RG and MGE abundance and microbial community composition were investigated in a field plot experiment. The relative abundances of RGs [sul1, sul2, tet(A), tet(M), tet(Q), tet(W), qacEΔ1/qacE] and MGEs [intI1, intI2, IncP-1, IncP-1ε and LowGC plasmids] in total community (TC)-DNA from organic fertilizers, bulk soil and maize rhizosphere were quantified by qPCR before/after fertilization and prior to maize harvest.

Revealing metabolic storage processes in electrode respiring bacteria by differential electrochemical mass spectrometry.

In this work we employ differential electrochemical mass spectrometry (DEMS) in combination with static and dynamic electrochemical techniques for the study of metabolic processes of electrochemically active bacteria. CO production during acetate oxidation by electrode respiring bacteria was measured, in-vivo and online with a sensitivity of 6.5 ⋅ 10 mol/s.

Correction to: Identification and characterization of a galacturonic acid transporter from and its application for fermentation processes.

[This corrects the article DOI: 10.1186/1754-6834-7-20.].

Design and Evaluation of a Boron Dipyrrin Electrophore for Redox Flow Batteries.

A boron dipyrrin (BODIPY) dye was designed as a molecular single-component electrophore for redox flow batteries. All positions of the BODIPY core were assessed on the basis of literature data, in particular cyclic voltammetry and density functional calculations, and a minimum required substitution pattern was designed to provide solubility, aggregation, radical cation and anion stabilities, a large potential window, and synthetic accessibility. In-depth electrochemical and physical studies of this electrophore revealed suitable cathodic behavior and stability of the radical anion but rapid anodic decomposition of the radical cation.

Determination of chemical oxygen demand (COD) using an alternative wet chemical method free of mercury and dichromate.

Worldwide, the standard methods for the determination of the important wastewater parameter chemical oxygen demand (COD) are still based on the use of the hazardous chemicals, mercury sulfate and chromium(VI). However, due to their properties they are meanwhile classified as "priority pollutants" and shall be phased out or banned in the frame of REACH (current European Chemical Law: Registration, Evaluation, Authorization and restriction of Chemicals) by the European Union. Hence, a new wet-chemical method free of mercury and chromium(VI) was developed.